Nanoscale domain engineering and characterization of ferroelectricdomains

Abstract

Nanoscale domain engineering in ferroelectric crystals is demonstrated down to a lateraldomain size of 25 nm in diameter using scanning force microscopy (SFM). The variousmodes of SFM are used to measure both the internal polarization field and external strayfield arising from bound surface charges in ferroelectric domains. From thesemeasurements the effective three-dimensional arrangement of ferroelectric domains isreconstructed. Domain switching is initiated applying strong electric fields between thetip and counter electrode. The size of freshly nucleated domains is found to depend dramaticallyon the switching conditions, i.e. the applied electric field strength and switchingtime. Domains of less than 100 nm in diameter result for an electric field Eexp >50 kV cm-1 applied for an ultra-short time period τexp <30 µs. Also, the coercive field of nanoscale ferroelectric domains in BaTiO3 singlecrystals is found to measure1.4 kV cm-1, much more than the bulk value. Analysis of the transient response duringdomain switching shows that domain nucleation proceeds withinless than 100 µs. With these tools we are able to record nanoscale hysteresisloops monitoring both the successful domain reversal and a well established materialcontrast between different ferroelectric structures with a resolution of better than 0.1%.